class Solution {
public:
    int maxProfit(vector<int>& prices, int fee) {
      int len = prices.size();
      if(len == 0||len == 1) return 0;
      vector<vector<int> >dp(len,vector<int>(2,0));
      dp[0][0] = -prices[0];
      for(int i = 1;i < len;i++){
        dp[i][0] = max(dp[i-1][0],dp[i-1][1] - prices[i]);
        dp[i][1] = max(dp[i-1][1],dp[i-1][0] + prices[i] - fee);
      }
      return dp[len-1][1];
    }
};	
